1. Field of the Invention
The present invention relates to a structure for reliably securing a plurality of batteries used in an electric vehicle to fixed positions in the electric vehicle.
2. Description of the Related Art
As a power supply for driving an electric vehicle, one type of arrangement that has normally been used is wherein a plurality of batteries are electrically series-connected to one another. When a battery of 12 V is used, for example, it is necessary to electrically series-connect nine or more batteries to one another to produce the desired electric power and to mount the so-connected batteries in the electric vehicle. Therefore, a structure has been employed wherein the desired number of batteries are suspended from a frame member of the vehicle body, which is located under the floor, with the batteries being accommodated in a battery box (see GB 1555773 A). Each of the batteries referred to above is heavy and the combined weight as a unit is very substantial. Thus, this type of structure is employed to lower the center of gravity of the vehicle body by disposing the heavy batteries on the lower side of the vehicle body.
Since the respective batteries are so heavy, it is necessary to firmly mount the batteries in the battery box. Therefore, there is known a structure disclosed in Japanese Utility Model Application Publication No. 58-52615, for example, in which the entire upper surface of the batteries is pressed by rubber presser member to thereby fixedly mount the batteries in the case.
The above conventional arrangement involves problems in that the rubber presser member also should be provided between the respective adjacent batteries and a process for detachably mounting a plurality of pieces of rubber presser members is required when the number of the batteries increases, particularly for execution of a maintenance process such as replacement of each battery, thereby making this type of maintenance process complex.
Also, the conventional arrangement creates the problem that since a plurality of batteries are accommodated within the battery box, the temperature of the batteries tends to increase beyond an effective use temperature, thereby causing a reduction in performance of each battery and decreasing the cycle life of each battery. Further, when the temperature of each battery is too high during its charging, the efficiency of charging of each battery is reduced.
Moreover, since the battery box is placed under the floor, when an opening or aperture for introducing cooling air into the battery box is opened, water, mud, dust, etc. tend to enter into the battery box through the opening or aperture.